A while back, when I was using Blender 2.49, I had lip synched a character using shape keys. At some point during an upgrade to Blender 2.5 and 2.6, I returned to this file and all the shape key animation I had done was missing. The armature animation, such as the up and down movement of the jaw bone, was all in place, but the lips no longer move to form each vowel the way they originally had. Does anyone know what might have happened to this data and if there is any way to retrieve it? Is it necessary to downgrade to 2.49 again? Would this even work, or is the data permanently lost? I spent a lot of time working on it so I would hate to think that all that effort was for nothing.

Any help you can offer is greatly appreciated.